Tyre Sealing Material Composition and Crown Positioning
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Solution Overview
Problem
Self-sealing tires face challenges in finding a suitable combination of properties for the sealing material and its proper positioning within the tire structure, which affects adhesion, flowability, and uniform distribution, leading to inefficiencies in air retention and weight distribution.
Innovation Solution
A sealing material comprising natural or synthetic elastomers, pre-crosslinked elastomers, low amounts of tackifying agents, reinforcing fillers, and homogenizing agents is used, applied between the carcass structure and an air-impermeable layer, with a cushion layer in the sidewall regions to maintain position and flowability, allowing rapid sealing of punctures without additional processing requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sealing material has high adhesion to puncture objects, then self-sealing performance is improved, but the material may adhere to tyre structure components (carcass plies, liner) preventing proper positioning
Solution Approach 1:
The sealing material is positioned only in specific radial and axial zones of the tyre, concentrated in the crown area rather than uniformly distributed. This localized placement ensures the material is available where punctures most commonly occur while limiting contact with carcass plies and liner in sidewall regions, thus preventing unwanted adhesion to structural components.
Solution Approach 2:
The sealing material is applied to the tyre structure before the tyre is fully assembled and inflated. This preliminary application allows the material to be positioned correctly in the crown area while the tyre structure is still accessible, preventing unwanted adhesion to components that will be in place during normal operation.
2Speed
If the sealing material flows rapidly to seal punctures, then self-sealing speed is improved, but the material may flow out of the puncture or redistribute non-uniformly during vehicle movement
Solution Approach 1:
The sealing material is concentrated in the crown area with controlled thickness, creating a localized reservoir that can rapidly flow to seal punctures. The material is absent or minimal in sidewall regions, preventing unwanted flow to areas where uniform distribution is not needed and where it could cause imbalance.
Solution Approach 2:
The sealing material is applied in sufficient quantity in the crown area to ensure rapid sealing of punctures, but not excessive quantity that would cause flow out of the puncture or redistribution to sidewall regions. The amount is optimized to provide just enough material for effective sealing without causing unwanted flow.
3Manufacturing precision
If additional processing steps are added to control sealing material positioning, then positioning precision is improved, but manufacturing complexity increases
Solution Approach 1:
The sealing material is applied to the tyre structure before final assembly and inflation, when the tyre is still in a semi-finished state. This preliminary application simplifies positioning control as the tyre structure is more accessible and requires no additional processing steps compared to applying material after assembly.
Solution Approach 2:
The sealing material is applied only in the crown area with specific radial and axial boundaries, concentrating the material where it is most needed. This localized application reduces the complexity of controlling material distribution across the entire tyre surface and eliminates the need for additional processing steps to prevent material in unwanted areas.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution ensures effective air retention, maintains sealing material distribution during vehicle movement, and simplifies tire manufacturing by avoiding the need for post-production treatments, with improved self-sealing performance and reduced air pressure loss.
Implementation Method 1
a pre-crosslinked styrene-butadiene rubber, in particular a hot polymerized styrene-butadiene rubber having a gel content of from 10% to 60% by weight
Implementation Method 2
said sealing material should adhere to the object causing the puncture
Implementation Method 3
may also flow into the puncture site when said object is removed, thus sealing the puncture
Data Source
Figure 1
Figure 2
AI summary
The present invention relates to a tyre for vehicle wheels, comprising: - a carcass structure of a substantially toroidal shape, having opposite lateral edges terminating in respective bead structures, said carcass structure comprising at least one carcass ply; - a belt structure applied in a radially external position with respect to said carcass structure, said belt structure comprising at least one belt layer; - a tread band applied in a radially external position with respect to said belt structure; - a pair of sidewalls applied laterally on opposite sides with respect to said carcass structure; - a substantially air-impermeable layer applied in a radially inner position with respect to said at least one carcass ply; - a layer of sealing material applied in a radially inner position with respect to said at least one carcass ply and, preferably, in a radially outer position with respect to said air-impermeable layer; wherein said sealing material comprises: from 55 phr to 95 phr, preferably from 65 phr to 90 phr, of at least one natural or synthetic elastomer; from 5 phr to 45 phr, preferably from 10 phr to 35 phr, of at least one pre-crosslinked elastomer, preferably a styrene-butadiene elastomer; from 5 to 50 phr, preferably from 20 phr to 40 phr, of at least one tackifying agent, and from 1 to 40 phr, preferably from 5 to 30 phr, of at least one reinforcing filler.